Applications of laser-induced breakdown spectroscopy – LIBS
Recently, there has been increased interest and demand in nearly all scientific research areas for experimental techniques that enable fast and unambiguous interpretation of the acquired data. This interest follows industrial requirements for fast and accurate material identification and analyses without lengthy laboratory techniques. The technique of LIBS involves formation of luminous plasma generated by focusing the radiation from a pulsed fixed-frequency laser (less then 1J/pulse) onto the surface of the sample to be analysed. The light emitted by the hot plasma is dispersed by a spectrometer and the characteristic emission lines produced by the excited elements during the plasma cooling make it possible to determine the elemental composition of the sample within the focus area. Detection limits of LIBS range from a few ppm to hundreds of ppm (w/w).
The additional advantages and applications of LIBS:
- With LIBS the entire interaction between the system and the target is purely optical. Thus, the analysis can be performed remotely, provided that an optical connection can be established between the instrument and the target, e.g. with the use of an optical fibre. For remote applications the target can be placed up to hundreds of meters away from the mobile LIBS instrument (sediments inside storage tanks, oil rigs, and rigid steel constructions).
- LIBS excels in instances where on-site, real-time, and on-line measurements in various production phases are required (e.g. for metal identification problems). Different types of steel (e.g. FV520, NAG, 17/4, and 18/13) can be identified simply by following some of the representative elements (e.g. Mo, Ni, and Ti).
- LIBS can detect the following elements – Be, U, I, Al, C, Ca, Mg, Cr, Pb, Si, Li, Hg, Sr, Rb, Ti, Fe, Ni, V, Mn, Mo, etc.
- The most appropriate applications of LIBS are those encountered in the nuclear and chemical industry, where quantitative or qualitative remote analysis, without any physical contact with the sample, is preferred. A mobile LIBS setup based on the optical fibre delivery system can be identified as a natural solution to some of the analytical problems where exposure of personnel to highly radioactive or toxic material is understandably undesirable.
- Various setups can be used for environmental monitoring. Specially engineered systems can be designed and assembled for each analytical problem, allowing fast decisions to be made concerning the identification of target materials which can then be immediately sorted and labelled.
- LIBS can be used for quantitative analysis with reasonable precision even for small samples provided a tightly focused beam is used for material ablation (this is limited by the focusing optics).
